Process for treating hydrocarbon oils



@et 9, 31934. A..LAzAR PROCESS FOR TREATING HYDROCARBON OILS Filed May9, 1931 @Smm Patented @et 9, iie

iwal?? PRCESS EUR HYDREUN Arthur Lazar, Associated, Caif., assigner toAssociated @il Company, San Francisco, Calif., a corporation ofCalifornia Application May 0, 1933i, Serial No. 536,220 9 Claims. (ci.ist) This invention relates to a process of treating oils and refersparticularly to mineral oils heavier than kerosene, especially thoseoils comprising the range from transformer oils to lubricat-I ing oils.

It is the object of this invention to improve the stability of suchmineral oils`by increasing their resistance to the effects of heat andoxygen.

J It is found that a properly applied and controlled oxidation step inthe treatment of mineral oils greatly improves such stability and thisprocess may be carried out with air in the presence of an adsorbentmaterial, such as clay, in such a manner that all undesirable reactionproducts formed by the oxidation are removed at the same time orthereafter. This is quite contrary to ordinary rening methods, whichhave always emphasized the fact that air should be excluded Ias much aspossible from all contact with theL 'inineral oils during treatment.

More specically, the literature and patents on clay treatment emphasizethe necessity of eliminating the presence of air during' a decolorizingprocess, because it is stated that the presence of air produced oils ofinferior color and outertone. Therefore, it has been proposed that suchtreatment be carried on in a closed system, or in an atmosphere of inertgas, especially when elevated temperatures are used.

Contrary to this conception and to the various methods known for thetreating of hydrocarbon oils heretofore mentioned, the followingdescribed process has for its essential feature the deliberate oxidationof such oils under certain conditions for the production of finishedoils of high stability,A for use where resistance to heat and oxidationis required.

Briefly, this process consists in oxidizing an oil with air, or otheroxidizing agents, at elevated temperatures either in the presence of anadsorbent clay or thereafter treating with an adsorbent clay.

When hydrocarbon oils are blown with air in the presence of an adsorbentmaterial, such as clay, the oxidation products which are formed arepartially volatilized with the discharged air and partially adsorbed bythe clay. In order to get the desired adsorption effect from the clay,

'it is necessary to maintain a temperature above 212 F., for an optimumtime period since it is well known that most natural clays containvarying amounts of chemically combined water and that the adsorptionreaction of the clay on the oil under treatment takes place during theheating process while the chemically combined water is split off.

It stands to reason that for oils of comparatively high volatility, asfor example, transformer oils, it would be too costly to use very hightemperatures during air blowing in the presence of an adsorbent, becausethis would cause high evaporation losses. A temperature of about 250 F.is found most suitable for this type of oil, but for oils of higherviscosity ranges and lower volatility it is possible to usemuch highertemperatures. lWhen using higher temperatures, for example temperaturesup to 800 F., quantities of hydro-carbon vapors and vapors of oxidizedproducts may be liberated which would be suflicient to form an explosivemixture with the air. For this reason it appears necessary to use acertain amount of steam together with 'the air in order to dilute thevapors and to remove them from the system more rapidly. By treating ahydrocarbon oil in this way, that is with the air, or with air andsteam, in presence of an adsorbent, such as clay, the volatile productsof oxidation together with a certain amount of light hydrocarbonsdistill over while the nonvolatile products of oxidation which are ofmore or less asphaltic or resinous nature are taken up by the adsorbent.

More specifically the hydrocarbon oil to be treated by this process mayhave been pretreated by any other well known `refining process. Itvmight be mentioned at this time that besides the ordinary chemicaltreating method with sulphuric acid and sludge removal, physicaltreatment with selective solvents is in use. A treatment with liquidsulphur'dioxide is the method preferred at this time as it has beenfound that oils so treated possess certain properties of stability notfound in acid treated oils. Liquid sulphur dioxide removes the bulk ofthe undesirable constituents in the form of a so-called extract whilethe portion of the oil which remains undissolved in the SO2 treatmentand which is the so-called raflinate represents the desirableconstituents. Such an SO2 raiiinate represents a particularly suitablemate- 100 rial for the process described in this specification, in sofar as the greater part of the unstable compounds will have already beeneliminated by the SO2 treatment. An oilwhich has been treated withliquid sulphur dioxide yields products of extraordinary high stabilitywhen finished according to the method described in the followingparagraphs and as illustrated in the accompanying ow sheet of drawing.

The oil, which has previously been treated with 110 sulphuric acid, orpreferably with liquid sulphur dioxide, and separated from the acidsludge or extract, is passed through a pipe 10 into a mixer 11 andagitated therein in any well known manner with the desired quantity ofadsorbent material, such as clay, introduced through the funnel 12. Themixture of oil and clay is then forced by pump 12 through a set ofheating coils 13 set in a furnace 14 wherein the temperature of themixture is raised, varying from 250 F. to 800 F. depending on the stockbeing treated, and the mixture is then passed into a surge tank 15equipped with a steam spray line 16 and an air spray line 17.

In surge tank 15, the heated mixture is subjected to the injection ofair, or other equivalent oxidizing agent, through spray 17 for a periodof time suilicient to obtain the desired oxidation effect on theundesired constituents of the oil and concurrently or thereafter steamis injected through the spray 16 to carry off undesired vaporizedoxidation products, which pass through a line 18 and condenser 19 to aseparator 20 wherein a separation of air, water and/or light reactionproducts takes place.

'I'he volume of throughput as well as the size of surge tank 15 permitsthe contacting time to be varied from a few minutes to several hours,and the contacting time and regulation of temperature during air, orsteam, injection may also be controlled by means of a by-pass'line 21and pump 22 whereby part, or all, of the mixture in surge tank 15 may becirculated through coils 13 and surge tank 15.

By thus oxidizing and removing oxidizable hydrocarbons at thetemperatures employed, the stability of the treated oils at similartemperatures is greatly enhanced inasmuch as hydrocarbons which normallywould become oxidized at such temperatures have been removed.

As a further precaution in removing all oxidized reaction products, themixture of treated oil and clay may be passed in part, or in whole, fromsurge tank 15 through line 23 to a steam stripper 24 wherein the lasttrace of volatile. matter may be removed as overhead while the strippedmixture is passed through a cooler 25, and filter 26 ready for use.

While the process herein described is substantially a continuous processwith, or without, the use of the recirculating line 21 and pump 22, thesteps of oxidation, adsorption, reductionand cooling in the presence ofclay may be carried out separately without affecting the desirableproperties of the finished oil. 4

In a typical run with a lubricating oil distillate, a predeterminedquantity of a mixture of oil and clay was circulated through coils 13and surge tank 15 until a temperature of about 700 F. was reached andduring the time of raising the temperature to this point air wascontinually injected through spray 17. As soon as the maximum desiredtemperature was reached, the air was cut oif as well as the heat appliedto coils 13 and the circulation continued with injection of steamthrough spray 16 until the viscosity and flash is increased to thedesired value by slow cooling, or to approximately 275 F., andthereafter the mixture is passed out through the stripper 24 withoutfurther steam treatment, cooler 25 and filter 26.

As a continuous process, oxidation, or oxidation and partial reductionmay take place at the same time in surge tank 15 while circulating partof the mixture as described, or not, while final reduction and coolingin the presence of the clay may take place in the stripper 24.

Table Edeleanu process and herein described trentment Acid treatment andclay only Gravity Flash Fire Viscosity S. U. et F.. Viscosity S. U. at210 F 49 Sulphur Color by reflected light (outertone).-.- Color bytransmitted light Color stability 0. 35% Green. Cherry Red. Good.

One of the outstanding characteristics of oils treated by this processis exceedingly high stability under conditions of use. The lighter gradeoils which have been treated by this process show an exceptionally longlife as insulating oils. This is indicated as well by the standardtesting methods as by their performance in actual service. While it washeretofore considered a very good result, i. e., if atransformer oilcould meet a Snyder life test of 25 to 30 days, it is now possible withthe procedure described above to manufacture transformer oils with alife test as high as 60 days. l

With regard to the heavier grade oils processed by the method describedit can be said that they show an exceptionally good performance as1ubricating oils for internal combustion engines, inasmuch as all thedetrimental constituents are removed which otherwise are responsible forgummy deposits in the engine and the formation of excessive carbon.

I claim as my invention:

1. The process of treating a hydrocarbon oil which comprises: subjectingsaid oil to the action of air and introduced steam at a temperaturebetween 350 and 800 F. but below the temperature of spontaneouscombustion in the presence of an adsorbent clay.

2. The process of treating a hydrocarbon oil which comprises: subjectingsaid oil to the action of air and introduced steam at a temperaturebetween 350 and 800 F. but below the temperature of spontaneouscombustion in the presence of an adsorbent clay, cooling the mixture ofoil and clay, and removing the adsorbent clay with its adsorbed matter.

3. The process ofv producing an improved lubricating oil whichcomprises: subjecting a treated lubricating distillate to the action ofoxygen while being heated slowly to a temperature between 350 and 800 F.but below the temperature of spontaneous combustion sucient to Vaporizeundesired products in the presence of adsorbent clay, cutting offapplied heat Iand oxygen, introducing steam to remove undesiredvaporized products, and removing the clay together with unvaporizedundesired products.

4. The process of producing an improved luf4; bricating oil whichcomprises: subjecting a treated lubricating distillate to the action ofoxygen while being heated to a temperature above 350 F. sufcient tooxidize part of the distillate and to vaporize undesired products in thepresence of adsorbent clay, cutting oi applied heat and oxygen,introducing steam to slowly reduce being heated to a temperature above350 F. sum- `cient to oxidize part of the distillate and to vaporizeundesired products in the presence of adsorbent clay, cutting oi appliedheat and oxy` gen, introducing steam to remove undesired vaporizedproducts, and removing the clay together with unvaporized undesiredproducts.

6. The process of producing an improved lubricating oil which comprises:subjecting a treated lubricating distillate to the action of oxygenwhile being heated to a temperature above 350 F. sumcient to oxidizepart of the distillate and to vaporize undesired products Ain thepresence of adsorbent clay, cutting oi applied heat and oxygen,introducing steam to reduce the temperature to approximately 275 F. andto remove undesired vaporized products, and removing the clay togetherwith unvaporized undesired products.

7. A process for producing an improved lubricating oil which comprises:treating lubricating fractions with liquid sulphur dioxide, separatingthe undissolved portion from the dissolved portion, agitating theundissolved portion with air and steam at temperatures between 350 and800 F. but below the temperature of spontaneous combustion in thepresence of adsorbent clay, continuing the steam after the air has beencut oi until suicient hydrocarbons have been distilled overhead to bringthe bottoms to a desired vis- .cosity, and removing the adsorbentmaterial with its containedmatter from the oil.

8. The process of producing an improved insulating oil which comprises:subjecting a treated insulating oil, or distillate, to the action ofoxygen while being heated to a temperature above 350 F. sumcient tooxidize part of the distillate and to vaporize undesirable products inthe presence of adsorbent clay, and removing the clay together withunvaporized undesirable products.

.9. A process for producing an improved insulating oil which comprises:treating insulating oil fractions with liquid sulphur dioxide,separating the undissolved portion from the dissolved portion, agitatingthe undissolved portion with air at a temperature above 212 F. in thepresence of adsorbent clay to eiect substantial oxidation of the oil,and removing the adsorbent material with its contained matter from theoil.

